scholarly journals Exploring the lower thermal limits for development of the human malaria parasite, Plasmodium falciparum

2019 ◽  
Vol 15 (6) ◽  
pp. 20190275 ◽  
Author(s):  
Jessica L. Waite ◽  
Eunho Suh ◽  
Penelope A. Lynch ◽  
Matthew B. Thomas
Keyword(s):  
Plasmodium Falciparum ◽  
Future Climate Change ◽  
Parasite Development ◽  
Temperature Dependent ◽  
Human Malaria Parasite ◽  
Thermal Limits ◽  
Degree Day ◽  
Extrinsic Incubation Period ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

The rate of malaria transmission is strongly determined by parasite development time in the mosquito, known as the extrinsic incubation period (EIP), since the quicker parasites develop, the greater the chance that the vector will survive long enough for the parasite to complete development and be transmitted. EIP is known to be temperature-dependent but this relationship is surprisingly poorly characterized. There is a single degree-day model for EIP of Plasmodium falciparum that derives from a limited number of poorly controlled studies conducted almost a century ago. Here, we show that the established degree-day model greatly underestimates the rate of development of P. falciparum in both Anopheles stephensi and An. gambiae mosquitoes at temperatures in the range of 17–20°C. We also show that realistic daily temperature fluctuation further speeds parasite development. These novel results challenge one of the longest standing models in malaria biology and have potentially important implications for understanding the impacts of future climate change.

scholarly journals Exploring the lower thermal limits for transmission of human malaria, Plasmodium falciparum

2019 ◽  
Author(s):  
Jessica L. Waite ◽  
Eunho Suh ◽  
Penelope A. Lynch ◽  
Matthew B. Thomas
Keyword(s):  
Plasmodium Falciparum ◽  
Anopheles Stephensi ◽  
Parasite Development ◽  
Temperature Dependent ◽  
Single Degree ◽  
Complete Development ◽  
Thermal Limits ◽  
Degree Day ◽  
Extrinsic Incubation Period ◽  
Impacts Of Climate Change

AbstractThe rate of malaria transmission is strongly determined by parasite development time in the mosquito, known as the extrinsic incubation period (EIP), since the quicker parasites develop, the greater the chance that the vector will survive long enough for the parasite to complete development and be transmitted. EIP is known to be temperature dependent but this relationship is surprisingly poorly characterized. There is a single degree-day model for EIP of Plasmodium falciparum that derives from a limited number of poorly controlled studies conducted almost a century ago. Here, we show that the established degree-day model greatly underestimates the rate of development of P. falciparum in both Anopheles stephensi and An. gambiae mosquitoes at temperatures in the range of 17-20°C. We also show that realistic daily temperature fluctuation further speeds parasite development. These novel results challenge one of the longest standing models in malaria biology and have potentially important implications for understanding the impacts of climate change.

scholarly journals Variable oxygen environments and DNMT2 determine the DNA cytosine epigenetic landscape of Plasmodium falciparum

2021 ◽  
Author(s):  
Artur Scherf ◽  
Elie Hammam ◽  
Samia Miled ◽  
Frederic Bonhomme ◽  
Benoit Arcangioli ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Mammalian Cells ◽  
Dna Methyltransferase ◽  
Cytosine Methylation ◽  
Parasite Development ◽  
Epigenetic Landscape ◽  
Human Malaria Parasite ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Oxidized Products

DNA cytosine methylation and its oxidized products are important epigenetic modifications in mammalian cells. Although 5-methylcytosine (5mC) was detected in the human malaria parasite Plasmodium falciparum, the presence of oxidized 5mC forms remain to be characterized.Here we establish a protocol to explore nuclease-based DNA digestion for the extremely AT-rich genome of P. falciparum (>80% A+T) for quantitative LC-MS/MS analysis of 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). We demonstrate the presence of 5hmC, 5fC and 5caC cytosine modifications in a DNMT2-only organism and observe striking ratio changes between 5mC and 5hmC during the 48-hour blood stage parasite development. Parasite-infected red blood cells cultured in different physiological oxygen concentrations revealed a shift in the cytosine modifications distribution towards the oxidized 5hmC and 5caC forms. In the absence of the canonical C5-DNA methyltransferase (DNMT1 and DNMT3A/B) in P. falciparum, we show that all cytosine modifications depend on the presence of DNMT2. We conclude that DNMT2 and oxygen levels are critical determinants that shape the dynamic cytosine epigenetic landscape in this human pathogen.

Commitment to sexual differentiation in the human malaria parasite, Plasmodium falciparum

Parasitology ◽  
2000 ◽  
Vol 121 (2) ◽  
pp. 127-133 ◽  
Author(s):  
T. G. SMITH ◽  
P. LOURENÇO ◽  
R. CARTER ◽  
D. WALLIKER ◽  
L. C. RANFORD-CARTWRIGHT
Keyword(s):  
Plasmodium Falciparum ◽  
Sexual Differentiation ◽  
Malaria Parasite ◽  
Human Malaria Parasite ◽  
Human Malaria ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

scholarly journals PfPDE1, a novel cGMP-specific phosphodiesterase from the human malaria parasite Plasmodium falciparum

2005 ◽  
Vol 392 (1) ◽  
pp. 221-229 ◽  
Author(s):  
Keizo Yuasa ◽  
Fumika Mi-Ichi ◽  
Tamaki Kobayashi ◽  
Masaya Yamanouchi ◽  
Jun Kotera ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Cyclic Nucleotide ◽  
Malaria Parasite ◽  
Catalytic Domain ◽  
Hydrolytic Activity ◽  
Human Malaria Parasite ◽  
Pde Inhibitors ◽  
Ic50 Value ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

This is the first report of molecular characterization of a novel cyclic nucleotide PDE (phosphodiesterase), isolated from the human malaria parasite Plasmodium falciparum and designated PfPDE1. PfPDE1 cDNA encodes an 884-amino-acid protein, including six putative transmembrane domains in the N-terminus followed by a catalytic domain. The PfPDE1 gene is a single-copy gene consisting of two exons and a 170 bp intron. PfPDE1 transcripts were abundant in the ring form of the asexual blood stages of the parasite. The C-terminal catalytic domain of PfPDE1, produced in Escherichia coli, specifically hydrolysed cGMP with a Km value of 0.65 μM. Among the PDE inhibitors tested, a PDE5 inhibitor, zaprinast, was the most effective, having an IC50 value of 3.8 μM. The non-specific PDE inhibitors IBMX (3-isobutyl-1-methylxanthine), theophylline and the antimalarial chloroquine had IC50 values of over 100 μM. Membrane fractions prepared from P. falciparum at mixed asexual blood stages showed potent cGMP hydrolytic activity compared with cytosolic fractions. This hydrolytic activity was sensitive to zaprinast with an IC50 value of 4.1 μM, but insensitive to IBMX and theophylline. Furthermore, an in vitro antimalarial activity assay demonstrated that zaprinast inhibited the growth of the asexual blood parasites, with an ED50 value of 35 μM. The impact of cyclic nucleotide signalling on the cellular development of this parasite has previously been discussed. Thus this enzyme is suggested to be a novel potential target for the treatment of the disease malaria.

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